Because the flood tide sets toward berth No.86 one hour after slack water, the berth is approached stern first and the vessel is moored port side to the inner dock. The vessel must not be stopped off the end of the oil dock because the ebb stream will set the vessel downstream. The manoeuvre consists in approaching the shoreline with the bow as close as possible to the deep water limit, then swinging the vessel to port with a tug made fast forward and the use of the bow thruster (if fitted) to position the vessel at a small angle and close to the deep water limit with the bow downstream. Thereafter, the vessel drifts in the flood stream toward the inner berth. The angle of approach of the vessel is controlled by a bow thruster and/or forward tug and an after tug. The usual practice calls for the second tug to be moored to the vessel's side once the vessel is turned around and ready to be pushed toward berth No.86. Evidence suggests that the vessel's headway was reduced in accordance with the prevailing conditions and circumstances as the vessel proceeded upriver toward the oil dock. However, as the vessel made her final approach toward the shoreline, the engine was not put astern in time to stop the vessel in the distance available. The additional water ballast added to meet the winter ballast condition affected the vessel's stopping capability. The vessel's headway reduced the bow thruster's efficiency. After mooring to the vessel, the LEONARDW. initially drifted parallel to the vessel. When the tug was ordered to push, she did not have enough time to place herself in a position to effectively push athwartships the vessel. Had the master known the exact manoeuvre to be performed, he might have been able to recommend to the pilot an appropriate reduction of speed.Analysis Because the flood tide sets toward berth No.86 one hour after slack water, the berth is approached stern first and the vessel is moored port side to the inner dock. The vessel must not be stopped off the end of the oil dock because the ebb stream will set the vessel downstream. The manoeuvre consists in approaching the shoreline with the bow as close as possible to the deep water limit, then swinging the vessel to port with a tug made fast forward and the use of the bow thruster (if fitted) to position the vessel at a small angle and close to the deep water limit with the bow downstream. Thereafter, the vessel drifts in the flood stream toward the inner berth. The angle of approach of the vessel is controlled by a bow thruster and/or forward tug and an after tug. The usual practice calls for the second tug to be moored to the vessel's side once the vessel is turned around and ready to be pushed toward berth No.86. Evidence suggests that the vessel's headway was reduced in accordance with the prevailing conditions and circumstances as the vessel proceeded upriver toward the oil dock. However, as the vessel made her final approach toward the shoreline, the engine was not put astern in time to stop the vessel in the distance available. The additional water ballast added to meet the winter ballast condition affected the vessel's stopping capability. The vessel's headway reduced the bow thruster's efficiency. After mooring to the vessel, the LEONARDW. initially drifted parallel to the vessel. When the tug was ordered to push, she did not have enough time to place herself in a position to effectively push athwartships the vessel. Had the master known the exact manoeuvre to be performed, he might have been able to recommend to the pilot an appropriate reduction of speed. The personnel available to establish a bridge resource management regime was not used to maximum advantage. Astern thrust was not requested in ample time for the stopping distance available. The tug did not have enough time to place herself in a position to effectively push the vessel athwartships. The speed of the vessel reduced the bow thruster's efficiency. There are no adequate aids to navigation to indicate the limit of the deep water south-east of berth No.86.Findings The personnel available to establish a bridge resource management regime was not used to maximum advantage. Astern thrust was not requested in ample time for the stopping distance available. The tug did not have enough time to place herself in a position to effectively push the vessel athwartships. The speed of the vessel reduced the bow thruster's efficiency. There are no adequate aids to navigation to indicate the limit of the deep water south-east of berth No.86. The DIAMOND STAR grounded while making her final approach off the Ultramar oil refinery dock in Lvis because the manoeuvres to slow down and swing the vessel into the flood tide were not carried out in ample time. The navigation personnel neither asked for nor were they given a full explanation by the pilot concerning the exact manoeuvres to be performed while docking.Causes and Contributing Factors The DIAMOND STAR grounded while making her final approach off the Ultramar oil refinery dock in Lvis because the manoeuvres to slow down and swing the vessel into the flood tide were not carried out in ample time. The navigation personnel neither asked for nor were they given a full explanation by the pilot concerning the exact manoeuvres to be performed while docking.